Multisite, Single Database, Single Login Problems...

I need to make my website allow for a single login process (login once for the main install and other multisites). I'm using 6.14 in this and it uses a single database so far. I feel like I've done everything humanly possible and I want to blame the host, but I have no honest reason to assume that the server is responsible for this--I think it's something I've done wrong in the code somewhere...

Here is more information on where I am right now -

Directory Structure:
public_html/drupal/
public_html/drupal/sites/default/
public_html/drupal/sites/site2.example.com/
public_html/drupal/sites/default/settings.php
public_html/drupal/sites/site2.example.com/settings.php
public_html/drupal/sites/site2.example.com/.htaccess

public_html/drupal/sites/default/settings.php CODE:

$db_prefix = array(
      'default'   => 'default_',
      'users'     => 'shared_',
      'sessions'  => 'shared_',
      'role'      => 'shared_',
      'authmap'   => 'shared_',
    );
Note: $base_url is commented out.

public_html/drupal/sites/site2/settings.php CODE:

$db_prefix = array(
      'default'   => 'site2_',
      'users'     => 'shared_',
      'sessions'  => 'shared_',
      'role'      => 'shared_',
      'authmap'   => 'shared_',
    );
Note: $base_url is commented out.

public_html/drupal/sites/site2/.htaccess CODE:

RewriteEngine on
RewriteCond %{HTTP_HOST} ^site2.example.com$ [OR]
RewriteCond %{HTTP_HOST} ^www.site2.example.com$
RewriteRule ^/?$ "http\:\/\/www\.example\.com\/drupal\/sites\/site2\/" [R=301,L]

Sub-domain information:
Main Domain: "www.example.com"
Sub-domain: "site2.example.com" -- Root set to "/public_html/drupal" (within CPANEL)

No matter what I've done, it seems to never fix this. I've updated from 6.whatever to 6.14 and that did nothing. I've tinkered with the domain names and that did nothing. I feel like I've read every document on the internet to no avail... I don't know what I'm doing wrong. I've posted about this to multiple forums and that got little-to-no results, too. I'm willing to provide almost any information if the above isn't enough, so if you could, PLEASE HELP before I die of hyperdrupaloidosis. :.P